A majority of the components of a hand held cutting torch have become relatively standardized in their function, structure and appearance. However, continuing development of the structure for mixing the oxygen and the fuel for the preheat flame of the torch has occurred in an effort to overcome long existent problems with hand held cutting torches. These problems include the susceptibility of the torch to potentially dangerous flashbacks or popping caused by the burning of the fuel-oxygen mixture within the torch itself. These flashbacks create high pressure shock waves within the torch which can rupture the wall of the torch or cause a chain reaction of flashbacks sending burning fuel and oxygen in one or both of the fuel and oxygen supply lines.
The flashback problem is worsened when using so-called low pressure fuels such as MAPP gas in a torch which is designed for higher pressure gases such as acetylene.
Other problems with prior art torches include incomplete or inconsistent mixing of the oxygen and fuel resulting in rough and unstable preheat flames.
It is an object of the present invention to provide a torch which obviates the tendency to flashback and which minimizes the potential danger of such flashbacks if they do occur.
It is a further object of the present invention to provide a cutting torch which minimizes the susceptibility of the torch to flashback danger while at the same time assuring adequate mixing of the fuel and oxygen, without unnecessarily increasing the cost of producing the torch.
It is still another object of the present invention to provide a cutting torch having a preheat tube which includes an improved mixing structure which is simple to manufacture and which assures proper mixing of the fuel and oxygen and proper control of the fuel flow to minimize the occurrence of flashbacks and which immediately extinguishes the flashbacks that do occur in order to prevent any dangerous sustained burning or chain reaction flashbacks.